H2A+NaOH→NaHAt=050 mL×0.225 mL×0.4 M010 milli mole10 milli molet=t0 milli mole0 milli mole10 milli mole
∴Ka1>>>Ka2
∵pKa=−[logKa1]
pKa=−log(10−6)
pKa=+6 log10
pKa=6
pKa2=−log[Ka2]
pKa2=−log10−12
pKa2=12
As the salt formed as amphoteric, for amphoteric salts pH can be calculated as
pH=pKa1+pKa22
pH=6+122
pH=9